DESCRIPTION infections in women are major causes of illness that also impacts on their newborn children and sexual partners. The mechanisms that protect the female urogenital mucosa from colonization and invasion by pathogens are not well understood. The recent discovery of antibiotic peptides originating from the human kidney and vagina provides an exciting opportunity to explore a novel mechanism of innate resistance to urogenital infections. The specific aims of this proposal are: 1. To isolate and characterize microgram amounts of native human genitourinary beta defensins (hGU- beta Ds), and to prepare these peptides in substantially larger amounts by solid-phase chemical synthesis. 2. To characterize the synthesis and processing of hGU- beta Ds; determine their sites of production, storage, and release; and examine the regulation of hGU-betaD synthesis by microbial substances, hormones and cytokines. 3. To clone and sequence the human GU- beta D gene, define its regulatory elements, and establish its chromosomal location. 4. To examine the activity of hGU- beta Ds against sexually transmitted bacterial pathogens and uropathogenic bacteria. Test organisms will include N. gonorrhoeae, C. trachomatis, E. coli and other Gram-negative bacteria. We will also test the activity of hGU- beta Ds against selected genitourinary tract commensals (L. acidophilus) and opportunists (C. albicans), and against certain sexually transmitted viruses (HSV and HIV-1). Antimicrobial testing will be performed under several conditions, including those simulating the pH, ionic composition, pO2 etc. found in vaginal and renal environments. The investigator's prior experience with endogenous peptide antibiotics structurally related to hGU- beta Ds will allow him to accomplish these specific aims effectively and expeditiously, building on the synergistic strengths of the laboratories of the investigator and co-investigator. In the long term, these studies may lead to novel ways to prevent and treat several of the most common and costly human afflictions: cystitis, pyelonephritis and the major sexually transmitted diseases.